Transmission apparatus of all-terrain vehicle

ABSTRACT

A transmission apparatus of an all-terrain vehicle includes: a non-stage transmission; a forward and backward movement switching device capable of switching to a forward movement position, a neutral position, or a backward movement position; and a shift operation device of rotary type for switching forward and backward movement disposed on a handle bar at a position adjacent to a handle grip. The shift operation device includes a rotary member for a shift operation and a locking mechanism for locking the rotary member so as not to move toward at least a position for backward movement from a position for neutral. The locking mechanism is configured to be handled by a hand griping the handle grip to make the locking mechanism unlocked.

BACKGROUND OF THE INVENTION

[0001] 2. Field of the Invention

[0002] The present invention relates to a transmission apparatus of anall-terrain vehicle having, in a power transmission path from an engineto drive wheels, a non-stage transmission, such as V belt non-stagetransmission, and a forward and backward movement switching devicecapable of switching to a forward movement position, neutral position,or backward movement position.

[0003] 2. Description of the Related Art

[0004] In this kind of all-terrain vehicle, a forward and backwardmovement switching device installed on the vehicle together with anon-stage transmission such as a V belt non-stage transmission isshifted to the forward movement position during regular running. Thespeed is automatically changed by the V belt non-stage transmissionduring running. If necessary, the vehicle is stopped once, the forwardand backward movement switching device is shifted to the backwardmovement position, and the vehicle is restarted running.

[0005] As a shift operation device for operating the forward andbackward movement switching device, conventionally, a lever type shiftoperation device is arranged in the neighborhood of a fuel tank which ispositioned in front of a seat of the vehicle. The forward and backwardmovement switching device is shifted to the forward movement position orbackward movement position by operating a shift lever of the lever typeshift operation device, as described in Japanese patent laid-openpublication No.8-337131 and Japanese patent publication No. 3040971,etc.

[0006] In the forward and backward movement switching device describedin the above-mentioned publications, the shift lever is arranged, forexample, in a gate plate having an H-type or I-type guide slit andswitches to the neutral position, forward movement position, or backwardmovement position by moving the shift lever along the guide slit.

[0007] In the vehicle that the shift operation device for switchingforward and backward movement positions is arranged near the fuel tankwhich is far away from a grip of a handle, the rider must release hishand from the grip in order to grasp the shift lever and perform theshift operation viewing the gate plate. Therefore, the rider cannotoperate the shift lever in the same riding posture as that duringrunning so that the shift operation is made troublesome. Further, in thecase that the shift lever is arranged near the fuel tank, the spacearound the legs of the rider is limited.

SUMMARY OF THE INVENTION

[0008] The present invention has been made to improve a shiftoperability of a forward and backward movement switching device of anall-terrain vehicle. More specifically, the objectives of the presentinvention are to provide a transmission apparatus of an all-terrainvehicle capable of enabling a rider to comfortably perform a shiftoperation while maintaining to grasp the grips by both hands and toeasily discriminate the conditions of the shift operation.

[0009] According to the present invention, a transmission apparatus ofan all-terrain vehicle comprises: a non-stage transmission disposed in apower transmission path from an engine to drive wheels; a forward andbackward movement switching device capable of switching to a forwardmovement position, a neutral position, or a backward movement position,the forward and backward movement switching device being disposed in thepower transmission path at a position near the engine; and a shiftoperation device of rotary type for switching forward and backwardmovement disposed on a handle bar at a position adjacent to a handlegrip, the shift operation device and the forward and backward movementswitching device being interlocked with each other, the shift operationdevice including a rotary member for a shift operation and a lockingmechanism for locking the rotary member so as not to move toward atleast a position for backward movement from a position for neutral, thelocking mechanism being configured to be handled by a hand, which is ina state of griping the handle grip, to make the locking mechanismunlocked.

[0010] By use of such a constitution, the rider can perform the shiftoperation for switching forward and backward movement almost in the sameriding posture as that during running without releasing a hand from thegrip, thus the shift operability for switching forward and backwardmovement is improved. Further, since the shift operation device isdisposed on the handle bar at a position adjacent to the handle grip,the space around the legs of the rider can be widely reserved. Moreover,since the locking mechanism of the shift operation device must be madeunlocked beforehand to perform the shift operation from the neutralposition to the backward movement position, the shift operation to thebackward movement can be automatically recognized.

[0011] Preferably, the rotary member is configured to be rotatable aboutan axis of the handle bar.

[0012] Preferably, the shift operation device includes a holder memberfixed on the handle bar, the rotary member being rotatably mounted onthe holder member.

[0013] Preferably, the locking mechanism includes locking notches formedon the holder member respectively corresponding to positions for forwardmovement, neutral, and backward movement, a locking pawl supported in aradially movable state by the rotary member so as to be selectivelyengaged with one of the locking notches, and an operating member formoving the locking pawl so as to be unengaged with the locking notch.

[0014] Preferably, the locking pawl is pressed outward in a radialdirection by an elastic member.

[0015] Preferably, the operating member includes an unlocking knobintegrally formed with the locking pawl and projected radially outwardfrom the rotary member.

[0016] According to the present invention having the constitutionsmentioned above, the rider can perform shift operations by rotating therotary member using the same finger which was used to push the unlockingknob to make the locking mechanism unlocked. Moreover, at any positionfor forward movement, neutral, or backward movement, the lockingmechanism can be made locked simply by releasing the finger from theunlocking knob. Therefore, the operability of shift operations performedby the hand gripping the handle grip can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of thepresent invention will become more apparent from the followingdescription taken in connection with the accompanying drawings, inwhich:

[0018]FIG. 1 is a plan view of an all-terrain vehicle to which thepresent invention is applied;

[0019]FIG. 2 is a left side view of the all-terrain vehicle shown inFIG. 1;

[0020]FIG. 3 is a right side view of the body frame and an engine of theall-terrain vehicle shown in FIG. 1;

[0021]FIG. 4 is an enlarged view of the section IV-IV shown in FIG. 3;

[0022]FIG. 5 is a right side view showing the rear end of the crankcaseand footbrake;

[0023]FIG. 6 is a plan view of FIG. 5;

[0024]FIG. 7 is an enlarged plan view showing the adjust bolt of thestopper mechanism;

[0025]FIG. 8 is a front view of the shift operation device;

[0026]FIG. 9 is a left side view (view of the arrow IX shown in FIG. 8)of the shift operation device;

[0027]FIG. 10 is a plan view of the shift operation device;

[0028]FIG. 11 is a sectional view of XI-XI shown in FIG. 9;

[0029]FIG. 12 is a sectional exploded view of XI-XI shown in FIG. 9;

[0030]FIG. 13 is a sectional view of XIII-XIII shown in FIG. 8; and

[0031]FIG. 14 is a sectional view of XIV-XIV shown in FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] [Outline of All-Terrain Vehicle]

[0033] In FIG. 1, for simplicity of explanation, “Left” and “Right”shown in the drawing indicate that the left direction and rightdirection viewed from a rider are the left direction and right directionof an all-terrain vehicle.

[0034] The all-terrain vehicle has a pair of front wheels 1 and a pairof rear wheels 2 and an engine 3 disposed between the wheels 1 and 2. Inthe neighborhood of the rear of the engine 3, a pair of bar-shaped steps8 and 9 are provided and in the neighborhood of the step 9 on the rightside, a footbrake 10 is installed in a rotatative state.

[0035] On the front side of the upper part of a vehicle body, a handlebar 12 is arranged, and behind the handle bar 12, a seat 13 is arranged,and above the front wheels 1 and the rear wheels 2, a front fender 15and a rear fender 16 are respectively arranged.

[0036] On the right side of a crankcase 4 of the engine 3, a V beltnon-stage transmission 5 is provided and on the rear of the crankcase 4,a gear type forward and backward movement switching device 6 is stored.Between a power output shaft 17 protruded from the rear end of theforward and backward movement switching device 6 and a final speedreducer 18 for driving the rear wheels, a drive shaft 19 is installedvia universal couplings.

[0037] At the right end of the handle bar 12, a right acceleration grip21 is provided in a rotative state and a front wheel brake lever 22 isalso provided, and at the left end of the handle bar 12, a left grip 23is fixed and a rear wheel brake lever 24 is provided. Furthermore, onthe handle bar 12 neighboring the left grip 23, a shift operation device26 for switching forward and backward movement of the vehicle isprovided, and the shift operation device 26 for switching forward andbackward movement is interlocked with an outside shift lever 73 of theforward and backward movement switching device 6 by a pair of cabletransfer devices 77 and 78 for transferring operational force.

[0038]FIG. 2 is a left side view of the all-terrain vehicle, wherein aV-type 2-cylinder engine 3 is loaded, and the engine 3 is stored andsupported in a body frame 27, and at the front end of the body frame 27,a radiator 28 is arranged.

[0039] The handle bar 12 is fixed to the upper end of a steering shaft11, and the steering shaft 11 is supported by a shaft support case (headpipe) 29 installed on the front of the body frame 27 in a rotativestate, and the lower end of the steering shaft 11 is interlocked with afront wheel steering device 30.

[0040] The final speed reducer 18 for driving the rear wheels issupported by the body frame 27 so as to freely swing in the verticaldirection via a swing arm 31 storing the drive shaft 19 and elasticallysupported by a rear suspension 33.

[0041] [V Belt Non-Stage Transmission]

[0042]FIG. 3 is a right side view of the body frame 27 and the engine 3,wherein the V belt non-stage transmission 5 is composed of a drivepulley 35 mounted on the crank shaft 7, a driven pulley 37 mounted on adriven shaft 36, and a V belt 38 wound between the pulleys 35 and 37 andin the same way as the well-known V belt non-stage transmission, due tochanges in the number of rotations of the engine and the load from therear wheel side, the effective pulley diameters of the respectivepulleys 35 and 37 is automatically adjusted, thus automatic non-stagespeed variation is realized.

[0043] [Forward and Backward Movement Switching Device]

[0044]FIG. 4 is an enlarged view of the section IV-IV shown in FIG. 3.Properly, it shows a state that the forward and backward movementswitching device 6 is cut and developed by a plane passing an inputshaft 40, a backward movement idle shaft 41, an intermediate outputshaft 42, and an output shaft 43 and in the drawing, the transversedirection (indicated in the drawing) of the vehicle and the transversedirection of the drawing are opposite to each other. The gear typeforward and backward movement switching device 6, as mentioned above,has the input shaft 40, the backward movement idle shaft 41, theintermediate output shaft 42, and the output shaft 43 and the inputshaft 40 is formed integrally with the driven shaft 36 of the V beltnon-stage transmission 5 and supported by the left and right side wallsof the crankcase 4 via a bearing 45. At the left end of the input shaft40, a backward movement input gear 50 is arranged, and at the right end,a forward movement input gear 51 is arranged, and between the inputgears 50 and 51, a shift sleeve 52 is spline-fit in an axially movablestate.

[0045] The backward movement input gear 50 has a dog pawl 50 a on theend face (right end face) on the side of the shift sleeve 52, is fitinto the input shaft 40 in a rotative state via the needle bearing, andmates with a backward movement output gear 55 of the intermediate outputshaft 42 via an idle gear 54 of the backward movement idle shaft 41. Theforward movement input gear 51 has a dog pawl 51 a on the end face (leftend face) on the side of the shift sleeve, is fit into the input shaft40 in a rotative state via the needle bearing, and mates with a forwardmovement output gear 56 of the intermediate output shaft 42. Theintermediate output shaft 42 is interlocked with the output shaft 40 viaa transmission gear 47 and an output gear 48. The output gear 43 isinterlocked with the power output shaft 17 (FIGS. 1 and 3) via the bevelgear mechanism not shown in the drawing. Further, FIG. 4 is a sectionaldevelopment elevation of the forward and backward movement device 6which is cut by a plane passing the shafts 40, 41, 42, and 43, so thatthe distance between the intermediate output shaft 42 and the inputshaft 40 displayed on the drawing is longer the actual distance.Therefore, the forward movement input gear 51 and the forward movementoutput gear 56 displayed on the drawing are away from each other.However, actually, they mate with each other as mentioned above.

[0046] On both end faces of the shift sleeve 52 in the axial direction,a backward movement dog pawl 58 opposite to the dog pawl 50 a of thebackward movement input gear 50 in a matable state and a forwardmovement dog pawl 59 opposite to the dog-pawl 51 a of the-forwardmovement input gear 51 in a matable state are formed, and in the middleof the shift sleeve 52 in the direction of the axis, an outer peripheralring slit 60 is formed, and a shift fork 61 is engaged with the ringslit 60. The shift fork 61 is fixed to a shift rod 62 supported by thecrankcase 4 in a transversely movable state and can move in thetransverse direction integrally with the shift rod 62.

[0047] The shift fork 61 and the shift sleeve 52 shown in FIG. 4 are inthe state of the neutral position and the dog pawls 58 and 59 of theshift sleeve 52 are provided respectively at predetermined intervals inthe direction of the axis from the dog pawls 50 a and 51 a of the inputgears 50 and 51. When the shift sleeve 52 is moved from the neutralposition toward the backward movement input gear 50 (in the direction ofthe arrow B3), the backward movement dog pawl 58 mates with the dog pawl50 a of the backward movement input gear 50 and enters the backwardmovement state. On the other hand, when the shift sleeve 52 is movedfrom the neutral position toward the forward movement input gear 51 (inthe direction of the arrow A3), the forward movement dog pawl 59 mateswith the dog pawl 51 a of the forward movement input gear 51 and entersthe forward movement state.

[0048] At the left end of the shift rod 62, a plurality of notches 65for positioning the shift rod 62 at the forward movement position,neutral position, or backward movement position at predeterminedintervals in the axial direction are formed and, a positioning ball 67pressed by a spring 66 is joined to the notches 65. The right end of theshift rod 62 is projected into a shift lever chamber 69 formed at theright rear end of the crankcase 4, and a shift pin 64 having a projectedtop is provided on the projected part thereof.

[0049] In an upper wall case 70 of the shift lever chamber 69, a shiftlever shaft 71 is supported in a rotative state and at the lower end ofthe shift lever shaft 71, an inner shift lever 72 extending forward andjoining to the shift pin 64 is fixed. The upper end of the shift levershaft 71 is projected upward from the shift lever chamber 69 and anouter shift lever 73 is fixed to it.

[0050]FIG. 6 is a plan view in which the outer shift lever 73 having aU-shaped section (vertically folded in two) is fixed to the shift levershaft 71 via an L-shaped bracket 75, extended from the shift lever shaft71 like two wings, and at the ends of both wings, wire joint holes 76are formed, respectively. To the joint holes 76, inner wire endterminals 77 b and 78 b of the cable transfer devices 77 and 78 arerespectively joined and the outer wire end terminals of the cabletransfer devices 77 and 78 are supported by a rear cylinder head 14 ofthe engine 3 via a bracket 79.

[0051] [Stopper Mechanism]

[0052] In FIG. 6, on the outer shift lever 73, to prevent the outershift lever 73 from rotation in the direction of the arrow B2 from theneutral position N to the backward movement position R, a stoppermechanism composed of an adjust bolt 83 and a stopper pin 86 is arrangedand the stopper mechanism is interlocked with the footbrake 10 via acable device 90 and can be released by the stepping operation on thefootbrake 10.

[0053] A stopper piece 80 is integrally formed with the outer shiftlever 73 so as to project almost perpendicularly (almost right backward)to the line connecting the joint holes 76. A nut 82 is welded to adownward-facing folded part 80 a of the stopper piece 80. The stopperadjust bolt 83 is screwed into the nut 82 in a posture along therotational direction of the outer shift lever 73. The adjust bolt 83 isfixed by a locking nut 84 in a desired projection amount.

[0054] In FIG. 6, the outer shift lever 73 is positioned in the neutralposition N, and the stopper pin 86 is arranged on the side of thebackward movement position R (in the direction of the arrow B2) at apredetermined interval K from an end face 83 a of the adjust bolt 83 inthe neutral position N.

[0055] The stopper pin 86 is arranged in the moving track of the adjustbolt 83 when the outer shift lever 73 rotates in the direction of thearrow B2 from the neutral position N to the backward movement position Rso as to freely enter or leave the moving track of the adjust bolt 83.The stopper pin 86 is connected to an inner wire 90 a of the cabledevice 90 for the stopper mechanism and supported in a pin case 88 in anaxially movable state. The stopper pin 86 is projected into the movingtrack of the adjust bolt 83 by the spring in the pin case 88 and leavesright backward from the moving track against the spring in the pin case88 by pulling the inner wire 90 a. The pin case 88 is fixed to thecrankcase 4 via a bracket 87.

[0056]FIG. 5 is a partial sectional right side view showing therelationship between the outer shift lever 73 and the footbrake 10. Thecable device 90 for the stopper mechanism is extended in theneighborhood of a brake shaft 92 and flexibly attached to a jointprojection 91 fixed to the brake shaft 92 or the footbrake 10. When thefootbrake 10 is stepped on, the joint projection 91 rotating integrallywith the footbrake 10 pulls the inner wire 90 a, thereby the stopper pin86 is pulled so as to leave from the moving track of the adjust bolt 83.

[0057]FIG. 7 is an enlarged plan view of the adjust bolt 83 of thestopper mechanism, and the end of the adjust bolt 83 is formed in acolumnar shape with an enlarged diameter, and in the base end face(right end face) of the adjust bolt 83, a joint slit 93 to which a minusscrewdriver can be joined is formed. When the screwdriver is joined intothe joint slit 93 and the projection amount of the adjust bolt 83 isadjusted, the gap K between the stopper pin 86 in the neutral positionand the end face 83 a of the adjust bolt 83 can be adjusted. The gap K,even if the end face 83 a of the adjust bolt 83 makes contact with thestopper pin 86, is adjusted so as to prevent the backward movement dogpawl 58 of the shift sleeve 52 in the neutral position N shown in FIG. 4from making contact with the dog pawl 50 a of the backward movementinput gear 50.

[0058] [Shift Operation Device and Locking Mechanism]

[0059] FIGS. 8 to 14 are detailed drawings of the shift operation device26 for switching forward and backward movement. In FIG. 8 showing afront view, the shift operation device 26 for switching forward andbackward movement, as mentioned above, is mounted on the handle bar 12neighboring the left grip 23 so that a rider can perform the shiftoperation in a state that he grasps the left grip 23.

[0060]FIG. 12 is a longitudinal sectional exploded view (an explodedview of the section XI-XI shown in FIG. 9) of the shift operation device26, which is composed of a holder case 95 fixed to the handle bar 12 anda rotor assembly 96 supported by the holder case 95 in a rotative statearound the axis of the handle bar 12.

[0061] The holder case 95 is structured so as to be vertically dividedinto two and upper and lower halved members 95 a and 95 b are joined toeach other. The rotor assembly 96 is composed of a cylindrical body 100integrally having a right reel 97 and a left dial part 98, a ring rubbercover 101 fit into the outer periphery of the dial part 98, and a ringcap 103 fixed to the left end face of the dial part 98 by a bolt 102.

[0062] A circular slit 105 for winding the inner wire is formed on thereel 97, and on the dial part 98, a locking mechanism composed of alocking pawl 108 and a coil spring 109 and a positioning mechanismcomposed of a positioning ball 110 and a coil spring 111 are provided.The locking pawl 108 is supported in the dial part 98 in a radiallymovable state, formed integrally with an unlocking knob 113, and pressedoutward in the radial direction by the coil spring 109 integrally withthe unlocking knob 113.

[0063] In FIG. 11 which is a longitudinal sectional view of the shiftoperation device 26 after being assembled, the locking pawl 108 isprojected rightward from the dial part 98 and engaged with one of threelocking notches 115 a, 115 b, and 115 c (FIG. 13) formed on the left endface of the holder case 95, for example, the neutral position lockingnotch 115 b. The unlocking knob 113 is projected outward from theperipheral surface of the dial part 98 and a knob cover 101 a of therubber cover 101 is fit on the outward projected part. When theunlocking knob 113 is pressed inward in the radial direction against thecoil spring 109, the locking pawl 108 is moved inward in the radialdirection so as to be unlocked from the locking notch 115 b.

[0064] The positioning ball 110 is stored in the dial part 98 in anaxially movable state, pressed rightward by the coil spring 111, andengaged with one of three positioning slits 116 a, 116 b, and 116 c(FIG. 13) formed on the left end surface of the holder case 95, forexample, the neutral positioning slit 116 b.

[0065]FIG. 13 is a sectional view along the line XIII-XIII shown in FIG.8. An inward-facing projection 118 is formed on the inner peripheralsurface of the holder case 95, and the projection 118 is engaged with apositioning hole 119 of the handle bar 12, thereby fixes the holder case95 so as to disable rotation.

[0066] The three locking notches 115 a, 115 b, and 115 c formed on theleft end face of the holder case 95 are formed at intervals in theperipheral direction, and the notch 115 a positioned on the front sideis a forward movement position locking notch, and the notch 115 bpositioned halfway is a neutral position locking notch, and the notch115 c positioned on the rear side is a backward movement positionlocking notch. The respective locking notches 115 a, 115 b, and 115 care open on the axis side, thus the locking pawl 108 can enter or leavefrom the axis side.

[0067] The positioning slits 116 a, 116 b, and 116 c are arranged at aphase difference of almost 180° from the locking notches 115 a, 115 b,and 115 c, and the slit 116 c positioned on the front side is a backwardmovement positioning slit, and the slit 116 b positioned halfway is aneutral positioning slit, and the slit 116 a positioned on the rear sideis a forward movement positioning slit.

[0068] In FIG. 10 showing a plan view, on the cover 101, a plurality ofnon-slip projections 121 are formed at intervals in the peripheraldirection and on the knob cover 101 a, a triangular mark 122 isprovided. On the other hand, on the surface of the holder case 95,symbols indicating the neutral position N, the forward movement position(drive position) D, and the backward movement position R are indicatedand as a mutual relationship between the positions N, D, and R, theforward movement position D is disposed before the neutral position N inthe peripheral direction, and the backward movement position R isdisposed behind the neutral position N in the peripheral direction.

[0069] [Cable Transfer Devices for Transferring the Shift OperationForce]

[0070]FIG. 14 is a sectional view along the line XIV-XIV shown in FIG.8. The first and second cable transfer devices 77 and 78 are insertedfrom underneath into the holder case 95, and inner wires 77 a and 78 athereof are respectively wound round the reel 97 from the rear side andfront side, and end terminals 77 b and 78 b are joined into joint holes125 and 126 of the reel 97. When the reel 97 is rotated, as shown inFIG. 14, in the direction of the arrow A1 from the neutral position N,the reel 97 pulls the inner wire 77 a of the first cable transfer device77 and loosens the inner wire 78 a of the second cable transfer device78. On the other hand, when the reel 97 is rotated inversely in thedirection of the arrow B1, the reel 97 pulls the inner wire 78 a of thesecond cable transfer device 78 and loosens the inner wire 77 a of thefirst cable transfer device 77.

[0071] Further, on the lower side of the reel 97, a notch 130 at a fixedangle is formed, and into the notch 130, an inward-facing projection 131formed on a lower holder case 95 b is projected, thus the maximumrotation range of the reel 97 is controlled.

[0072] Both cable transfer devices 77 and 78 reach the neighborhood ofthe handle shaft 11 along the handle bar 12 shown in FIG. 2, extenddownward in the neighborhood of the handle shaft 11, and respectivelyextend backward along the left and right pipes of the body frame 27,thus as shown in FIG. 6, the inner wires 77 a and 78 a are connected toboth ends of the outer shift lever 73.

[0073] [Operation and Function]

[0074] [Neutral State]

[0075] When the rotor assembly 96 is arranged in the neutral position Nas shown in FIGS. 8 to 10, i.e., when the unlocking knob 113 and themark 122 are fit to the neutral position N, as shown by a solid line inFIG. 13, the locking pawl 108 is joined to the neutral position lockingnotch 115 b, thus the rotor assembly 96 is locked at the neutralposition N and can move toward neither the forward movement position D(in the direction of the arrow A1) nor the backward movement position R(in the direction of the arrow B1). Further, the positioning ball 110 isalso joined to the neutral positioning slit 116 b as shown by a solidline in FIG. 13 and the rotor assembly 96 is prevented from play in therotational direction.

[0076] In FIG. 6, the outer shift lever 73 is also arranged in theneutral position N, so that the adjust bolt 83 is opposite to thestopper pin 86 projected with a predetermined gap K, thereby, the outershift lever 73 is prevented from moving toward the backward movementposition R (in the direction of the arrow B2). Namely, moving from theneutral position to the backward movement position is double locked bythe stopper mechanism shown in FIG. 6 and the locking mechanism of theshift operation device 26 shown in FIG. 11.

[0077] In FIG. 4, the shift sleeve 52 is arranged in the neutralposition N and the left and right dog pawls 58 and 59 of the shiftsleeve 52 are away from the dog pawls 50 a and 50 b of the input gears50 and 51 for backward movement and forward movement. Therefore, theinterval between the input shaft 40 and the input gears 50 and 51 is ina state that the transmitting of power is interrupted.

[0078] [Shift from the Neutral Position to the Forward MovementPosition]

[0079] To shift from the neutral position to the forward movementposition, the unlocking knob 113 shown in FIG. 9 is pushed to unlock thelocking pawl 108 shown in FIG. 11 and the rotor assembly 96 is rotatedtoward the forward movement position D in the direction of the arrow A1.Namely, when the unlocking knob 113 shown in FIG. 11 is pushed byfinger, the locking pawl 108 is dislocated downward from the neutralposition locking notch 115 b, and the rotor assembly 96 is rotated inthe direction of the arrow A1 shown in FIG. 13 with the unlocking statekept, and at the point of time when the positioning ball 110 is joinedinto the forward movement positioning slit 116 a on the rear side, theunlocking knob 113 (FIG. 9) is released from the finger. Then, as shownby a hypothetical line in FIG. 13, the locking pawl 108 moving up to theforward movement position locking notch 115 a is automatically fit intothe forward movement position locking notch 115 a by the coil spring109. By doing this, the rotor assembly 96 is locked in the forwardmovement position D so as to prevent from moving in directions of thearrows A1 and AB1. Further, the positioning ball 110 is joined into theforward movement positioning slit 116 a on the rear side, so that therotor assembly 96 is prevented from play in the rotational direction.

[0080] In FIG. 14, in correspondence with the rotation of the rotorassembly 96 toward the forward movement position D, the inner wire 77 aof the first cable transfer device 77 is pulled and the inner wire 78 aof the second cable transfer device 78 is loosened.

[0081] In FIG. 6, when the inner wire 77 a of the first cable transferdevice 77 is pulled, the outer shift lever 73 is rotated in thedirection of the arrow A2 from the neutral position N to the forwardmovement position D. Integrally with the rotation of the outer shiftlever 73 toward the arrow A2, the shift lever shaft 71 and the innershift lever 72 shown in FIG. 4 are also rotated, and the shift rod 62 ismoved toward the forward movement position D (in the direction of thearrow A3), and the forward movement dog pawl 59 of the shift sleeve 52mates with the dog pawl 51 a of the forward movement input gear 51.

[0082] In such a forward movement state, the power transferred into theforward and backward movement switching device 6 from the engine 3 shownin FIG. 1 via the V belt non-stage transmission 5 is transferred to theoutput shaft 43, as shown in FIG. 4, via the input shaft 40, the shiftsleeve 52, the dog pawls 59 and 51 a, the forward movement input gear51, the forward movement output gear 56, the intermediate output shaft42, the transfer gear 47, and the output gear 48 and transferred to therear wheels 2, as shown in FIG. 1, via the power output shaft 17, thedrive shaft 19, and the final speed reducer 18 for the rear wheels.

[0083] [Shift from the Forward Movement Position to the NeutralPosition]

[0084] To shift from the forward movement position to the neutralposition, the unlocking knob 113 shown in FIG. 9 is pushed to unlock thelocking paw 118 and the rotor assembly 96 is rotated in the direction ofthe arrow B1 from the forward movement position D to the neutralposition N.

[0085] The basic operation is the same as that of the shift from theneutral position to the forward movement position, so that theexplanation will be simplified. In FIG. 13, the locking pawl 108returning to the neutral position N is automatically fit into theneutral position locking notch 115 b by the coil spring 109 and locksthe rotor assembly 96 in the neutral position N. Further, thepositioning ball 110 is joined into the neutral positioning slit 116 b.

[0086] [Shift from the Neutral Position to the Backward MovementPosition]

[0087] To shift from the neutral position to the backward movementposition, both the stopper release operation by the footbrake 10 shownin FIG. 1 and the unlocking operation by the unlocking knob 113 shown inFIG. 11 are necessary. Namely, in FIG. 5, when the footbrake 10 isstepped on, the stopper pin 86 is pulled via the joint projection 91 andstopper mechanism cable device 90 and separated from the moving track ofthe adjust bolt 83 shown in FIG. 6, thereby, the stopper mechanism isreleased. In addition to the release operation, when the unlocking knob113 of the shift operation device 26 shown in FIG. 11 is pushed, thelocking pawl 108 is dislocated and unlocked from the neutral positionlocking notch 115 b. In the state that the locking mechanism and stoppermechanism are released like this, the rotor assembly 96 is rotated inthe direction of the arrow B1 from the neutral position N to thebackward movement position R shown in FIG. 13.

[0088] When the unlocking knob 113 is released from finger at the pointof time when the positioning ball 110 is joined into the backwardmovement positioning slit 116 c on the front side, the locking pawl 108moving up to the backward movement position locking notch 115 c isautomatically fit into the backward movement position locking notch 115c by the coil spring 109. By doing this, the rotor assembly 96 is lockedin the backward movement position R so as to prevent it from moving indirections of the arrows A1 and AB1. Further, the positioning ball 110is joined into the backward movement positioning slit 116 c on the frontside, thereby the rotor assembly 96 is prevented from play in therotational direction.

[0089] In FIG. 14, in correspondence with the rotation of the rotorassembly 96 toward the backward movement position D, the inner wire 78 aof the second cable transfer device 78 is pulled and the inner wire 77 aof the first cable transfer device 77 is loosened.

[0090] In FIG. 6, the stopper pin 86 is pulled in by the steppingoperation of the footbrake 10, so that the moving track of the adjustbolt 83 toward the backward movement position D is put into the openstate, and the inner wire 78 a of the second cable transfer device 78 ispulled in this state, thus the outer shift lever 73 is rotated in thedirection of the arrow B2 from the neutral position N to the backwardmovement position R. Integrally with the rotation of the outer shiftlever 73 in the direction of the arrow B2, the shift lever shaft 71 andthe inner shift lever 72 shown in FIG. 4 are also rotated, and the shiftrod 62 is moved in the direction of the arrow B3 toward the backwardmovement position R, and the backward movement dog pawl 58 of the shiftsleeve 52 mates with the dog pawl 50 a of the backward movement inputgear 50.

[0091] When a vehicle is moved backward with the footbrake 10 in FIG. 6being returned to OFF after shifting to the backward movement positionas mentioned above, the stopper pin 86 intends to return to theprojection state from the pull-in state by the spring in the pin case88. However, the end face of the stopper pin 86 makes contact with theside of the adjust bolt 83 in the backward movement position R and thestopper pin 86 is kept in the pull-in state. Further, the strength ofthe spring set in the pin case 88 is weaker than that of the returnspring of the footbrake 10 and even when the stopper pin 86 is stoppedin the pull-in state as mentioned above, by the absorption operation dueto bending of the cable device 90 and the strength of the footbrakereturn spring, the footbrake 10 is returned to its normal off state.

[0092] In the backward movement state, the power transferred into theforward and backward movement switching device 6 from the engine 3 shownin FIG. 1 via the V belt non-stage transmission 5 is transferred to theoutput shaft 43, as shown in FIG. 4, via the input shaft 40, the shiftsleeve 52, the dog pawls 59 and 50 a, the backward movement input gear50, the backward movement idle gear 54, the backward movement outputgear 55, the intermediate output shaft 42, the transfer gear 47, and theoutput gear 48 and transferred to the rear wheels 2, as shown in FIG. 1,via the power output shaft 17, the drive shaft 19, and the final speedreducer 18 for the rear wheels.

[0093] [Shift from the Backward Movement Position to the NeutralPosition]

[0094] To return to the neutral position from the backward movementposition, the stopper release operation by the footbrake 10 shown inFIG. 1 is not necessary and the shift operation can be performed only bythe unlocking operation by the unlocking knob 113 shown in FIG. 11.Namely, when the unlocking knob 113 of the shift operation device 26shown in FIG. 9 is pushed, the locking pawl 108 in the backward movementposition R shown in FIG. 13 is dislocated from the backward movementposition locking notch 115 c toward the axis of the handle bar 12 and inthis unlocked state, the rotor assembly 96 is rotated in the directionof the arrow A1 from the backward movement position R to the neutralposition N.

[0095] In correspondence with the aforementioned shift operation, theouter shift lever 73 shown in FIG. 6 is pulled by the first cabletransfer device 77, thereby returned in the direction of the arrow A2from the backward movement position R to the neutral position N. At thistime, the adjust bolt 83 is moved in the direction of the arrow A2 bysliding on the end of the stopper pin 86 in the pull-in state, and atthe point of time when the adjust pint 83 is dislocated from the endface of the stopper pin 86, the stopper pin 86 is automaticallyprojected by the spring in the pin case 88 and the mechanism is returnedto the stopper operation state.

[0096] [Adjustment of the Stopper Mechanism]

[0097] In FIG. 4, to prevent the shift sleeve 52 in the neutral positionN from making contact with the dog pawls 50 a and 51 a of the inputgears 50 and 51 due to a manufacture error or play in the axialdirection, the gap K between the adjust bolt 83 and the stopper pin 86shown in FIG. 7 is adjusted. Concretely, the gap K is adjusted so as toprevent the dog pawl 58 of the shift sleeve 52 shown in FIG. 4 frommaking contact with the dog pawl 50 a of the backward movement inputgear 50 even when the adjust bolt 83 makes contact with the stopper pin86.

[0098] As shown in FIG. 1, the outer shift lever 73 is arranged at theright rear end of the crankcase 4, and the tool joint slit 93 of theadjust bolt 86 shown in FIG. 7 is directed right forward, thus a rideror an operator can simply loosen the locking nut 84 from the side of thevehicle and adjust the rotation of the adjust bolt 86.

[0099] In this embodiment, the stopper mechanism is provided on theouter shift lever 73 arranged above the right rear end of the crankcase4, and the stopper mechanism is interlocked with the footbrake 10arranged on the right step 9, so that the cables placed from thefootbrake 10 to the stopper mechanism may be short, and only externalcables may be used, thereby, the mounting operation can be simplified.

[0100] In the above-mentioned embodiment, since the stopper mechanism,which is interlocked with the brake device, is provided in order toprevent the switching rotary part of the forward and backward movementswitching device from moving to the backward movement position from theneutral position, a brake operation is needed in order to perform abackward shift by the forward and backward movement switching device.Therefore, the shift operation to backward movement can be automaticallyrecognized, and during the shift operation, the vehicle can be preventedfrom moving back and forth.

[0101] In the above-mentioned embodiment, since the locking mechanism ofthe shift operation device and the stopper mechanism of the forward andbackward movement switching device interlocked with the brake device areprovided, to perform the shift operation from the neutral position tothe backward movement position, the double locking mechanism must bereleased beforehand, thereby, the recognition of the shift operation tothe backward movement can be made surer.

[0102] Some modifications can be applied to the above-mentionedembodiment as follows.

[0103] (1) The stopper mechanism composed of the stopper pin and adjustbolt may be interlocked with a brake device of a hand lever type.

[0104] (2) As the forward and backward movement switching device, astructure that forward movements of two steps, neutral and backwardmovements can be switched mutually may be used.

[0105] Furthermore, the arrangement location of the forward and backwardmovement switching device is not limited to the rear part of the engineunit including the transmission, for example, it may be arranged on theside, front side, or in other places.

[0106] (3) As the switching rotary part of the forward and backwardmovement switching device in which the stopper mechanism interlockedwith the brake device is provided, the inner shift lever 72 may be usedin stead of the outer shift lever 73 shown in FIG. 5.

[0107] (4) Other than the V belt non-stage transmission, for example, atorque converter for an all-terrain vehicle may be used.

[0108] Although the invention has been described in its preferredembodiments with a certain degree of particularity, obviously manychanges and variations are possible therein. It is therefore to beunderstood that the present invention may be practiced otherwise than asspecifically described herein without departing from the scope andspirit thereof.

What is claimed is:
 1. A transmission apparatus of an all-terrainvehicle comprising: a non-stage transmission disposed in a powertransmission path from an engine to drive wheels; a forward and backwardmovement switching device capable of switching to a forward movementposition, a neutral position, or a backward movement position, saidforward and backward movement switching device being disposed in saidpower transmission path at a position near said engine; and a shiftoperation device of rotary type for switching forward and backwardmovement disposed on a handle bar at a position adjacent to a handlegrip, said shift operation device and said forward and backward movementswitching device being interlocked with each other, said shift operationdevice including a rotary member for a shift operation and a lockingmechanism for locking said rotary member so as not to move toward atleast a position for backward movement from a position for neutral, saidlocking mechanism being configured to be handled by a hand, which is ina state of griping said handle grip, to make said locking mechanismunlocked.
 2. A transmission apparatus of an all-terrain vehicleaccording to claim 1, wherein said rotary member is configured to berotatable about an axis of said handle bar.
 3. A transmission apparatusof an all-terrain vehicle according to claim 2, wherein said shiftoperation device includes a holder member fixed on said handle bar, saidrotary member being rotatably mounted on said holder member.
 4. Atransmission apparatus of an all-terrain vehicle according to claim 3,wherein said locking mechanism includes locking notches formed on saidholder member respectively corresponding to positions for forwardmovement, neutral, and backward movement, a locking pawl supported in aradially movable state by said rotary member so as to be selectivelyengaged with one of said locking notches, and an operating member formoving said locking pawl so as to be unengaged with said locking notch.5. A transmission apparatus of an all-terrain vehicle according to claim4, wherein said locking pawl is pressed outward in a radial direction byan elastic member.
 6. A transmission apparatus of an all-terrain vehicleaccording to claim 4, wherein said operating member includes anunlocking knob integrally formed with said locking pawl and projectedradially outward from said rotary member.